The disclosure relates generally to additive manufacturing, and more particularly, to an additive manufactured component with an enlarged width area in a channel at an interface where a pair of melting beam fields meet or overlap.
The pace of change and improvement in the realms of power generation, aviation, and other fields has accompanied extensive research for manufacturing components used in these fields. Conventional manufacture of metallic, plastic and metal ceramic components generally includes milling or cutting away regions from a slab of metal before treating and modifying the cut metal to yield a part, which may have been simulated using computer models, e.g., in drafting software. Manufactured components which may be formed from metal can include, e.g., airfoil components for installation in a turbomachine such as an aircraft engine or power generation system. The development of additive manufacturing can reduce manufacturing costs by allowing such components to be formed more quickly, with unit-to-unit variations as appropriate. Among other advantages, additive manufacture can directly apply computer-generated models to a manufacturing process while relying on less expensive equipment and/or raw materials.
Additive manufacturing (AM) includes a wide variety of processes of producing a component through the successive layering of material rather than the removal of material. As such, additive manufacturing can create complex geometries without the use of any sort of tools, molds or fixtures, and with little or no waste material. Instead of machining components from solid billets of material, much of which is cut away and discarded, the only material used in additive manufacturing is what is required to shape the component.
Additive manufacturing techniques typically include taking a three-dimensional computer aided design (CAD) file of the component to be formed, electronically slicing the component into layers, e.g., 18-102 micrometers thick, and creating a file with a two-dimensional image of each layer, including vectors, images or coordinates. The file may then be loaded into a preparation software system that interprets the file such that the component can be built by different types of additive manufacturing systems. In 3D printing, rapid prototyping (RP), and direct digital manufacturing (DDM) forms of additive manufacturing, material layers are selectively dispensed, sintered, formed, deposited, etc., to create the component.
In metal powder additive manufacturing techniques, such as direct metal laser melting (DMLM) (also referred to as selective laser melting (SLM)), metal powder layers are sequentially melted together to form the component. More specifically, fine metal powder layers are sequentially melted after being uniformly distributed using an applicator on a metal powder bed. Each applicator includes an applicator element in the form of a lip, brush, blade or roller made of metal, plastic, ceramic, carbon fibers or rubber that spreads the metal powder evenly over the build platform. The metal powder bed can be moved in a vertical axis. The process takes place in a processing chamber having a precisely controlled atmosphere of inert gas, e.g., argon or nitrogen. Once each layer is created, each two dimensional slice of the component geometry can be fused by selectively melting the metal powder. The melting may be performed by a melting beam source such as a high powered laser, e.g., a 100 Watt ytterbium laser, to fully weld (melt) the metal powder to form a solid metal. The melting beam source moves in the X-Y direction using, e.g., scanning mirrors, and has an intensity sufficient to fully weld (melt) the metal powder to form a solid metal. The metal powder bed is lowered for each subsequent two dimensional layer, and the process repeats until the component is completely formed.
In order to create more components faster or create certain larger components faster, some metal additive manufacturing systems employ multiple melting beam sources, such as high powered lasers, that work together to form a component. Where multiple melting beam sources are used, the melting beams must be precisely aligned to create high quality components. For example, misalignment of a pair of melting beam sources during manufacture of components with cooling channels therein (such as those used in the power generation, aviation and other fields) can be a challenge. In particular, a misalignment of melting beam sources can create a cooling channel with a step in the channel at an interface of the melting beam sources' fields. The interface may be a plane where the fields meet, or a three dimensional region where the fields overlap. To further explain, FIGS. 1-3 show a component 10 including a stepped channel 12 formed at an interface 14 where fields of the melting beam sources (not shown) meet. FIG. 1 shows a longitudinal cross-sectional view of component 10 including stepped channel 12; FIG. 2 shows a schematic perspective view of stepped channel 12; and FIG. 3 shows a lateral cross-sectional view of stepped channel 12. One melting beam source creates component 10 and stepped channel 12 on one side of interface 14, while another melting beam source creates them on the other side of interface 14. Here, a misalignment 16 of melting beam sources (not shown) used to create the channel creates a step 18 in stepped channel 12 at an interface 14. Step 18 might be up to 0.1-0.2 millimeter (mm) in a well calibrated machine, but steps up to 0.5 mm are possible. Steps as small as 0.1 mm can result in a reduction in flow in stepped channel 12 area in the order of, for example, 5% to 20%. In any event, step 18 creates a reduction of the fluid flow in stepped channel 12.